The variable swimming speeds exhibited by spermatozoa appear to be controlled by intrinsic and extrinsic factors. In response to extraneous environmental conditions, acetylcholine, which functions as mediator of impulse transmission in a variety of excitable systems, may serve a similar function in regulating sperm motility. We are investigating the effects of various anticholinesteratic and acetylcholine receptor blocking agents and drugs known to inhibit choline acetyltransferase, causing dose-dependent increase and decrease in spermatozoan motility. We are trying to determine the precise location of receptor sites of acetylcholine, the electrophysiological properties of sperm cells and influence of various heavy metals on the spermatozoan motility. Finally, we want to determine the physicochemical machinery in the regulation of flagellar performance of spermatozoa ranging from immobility during early development, through acquisition of motile capacity, to a rapid rate of undulation at the time of fertilization. BIBLIOGRAPHIC REFERENCES: Chakraborty, J. and Nelson, L: Fate of surplus sperm in the fallopian tube of the white mouse, Biol. Reprod., 12; 455-463, 1975. Chakraborty, J. and Nelson, L.: Fine structural localization of cholinesterases in the reproductive tract of the male white mouse. Biol. Reprod., 13; 397-407, 1975.